Major Oil leak Camshaft

[Nditiz1]

So I dropped out my 2.7 in order to address 2 major oil leaks. 1 is coming from the 4/5/6 side between the chain case and the cam tower. I'm going to pull off the sprocket to check the camshaft seal. Besides having to recheck timing after this endeavor do I need to go as far as removing all the rocker shafts to inspect. I realize if the seal has been pinched I would need to remove all the rockers to fix and replace. Just want some expert advice on how far I need to go. Also, would this be the only place it could leak is from this red seal that looks to be in place when I look from the side?

Secondly, should the washer on the sprocket be where it is? It almost looks like it should be centered more, but I believe it is a dished washer under the nut so maybe not?

[boyt911sc]

Nick,

I could see from the picture that you have nyloc type fasteners in your newly rebuilt motor. People who attended the recent Engine Rebuilding Workshop 2021 were advised not use these type of fastens inside the motor. Replace them with the standard metric fasteners with wavy steel lock washers. If you have disassembled several 911 engines, you will find no nyloc type fasters inside the motor. They are only used outside the engines from the factory. Replace them now before you install the chain housing covers.

Did you repair the backside of the chain housing covers with JB weld? There are several spots behind the chain housing covers that have epoxy to seal the studs/posts. PM me, I might be able to help you with your leak problem.

Tony

[dannobee]

The cam o-ring and gasket are accessible by removing the tensioner, cam timing gears, woodruff key, and cam spacing washers. There are three bolts holding the cam retainer to the head (cam carrier). The gasket and o-ring are under the cam retainer.

But the #4 intake rocker shaft is also in that area and could be leaking.

And as Tony said, the glue/sealant on the back side of the chain housing could be seeping. In that case, you'll need to remove the chain housing to get it all clean enough to do the job correctly (the two pins holding the plastic chain guide are supposed to have sealant, too, if they look dry, you won't need to remove the chain housing). But if you've already removed the cam gear and cam retaining plate, you're almost there anyway (other than some swearing and cajoling the housing to clear the chain). And as Tony said, no nylocks inside. If you look closely at your pic, you can see that the end of the stud isn't protruding through the nylon part of the nut.

And of course, retime that cam after it all goes back together. Setting the crank to Z1 first can help with that.

[Nditiz1]

Thanks to both,

Here is some more exploratory surgery. To your point dannobee, I'm not sure how the pins holding the plastic chain guide would be dry. Isn't oil being slung all around in the chain case?

Is the solution to this leak a new gasket with Locktite 574?

[boyt911sc]

You could see from your pictures that there was no adhesion between the paper gasket and the cam tower mating surfaces. I apply on both sides of the paper gasket a thin uniform coat of Loctite 574 and have good results. The only drawback is that the paper gasket becomes a one-time use only but prevents oil leaks. The paper gasket is cheap and using Loctite 574 gives me good results. So I stick to this procedure.

Tony

[Nditiz1]

Thanks Tony,

I will get a new gasket and lather up with 574 and bolt it back together and recheck timing.

Should I go as far as removing the chain case for any reason?

[dannobee]

If you're confident that the leak was from the cam, then no need to pull off the housing. But you can look behind the chain housing and verify that there's sealer/glue on the guide and tensioner pins.

Personally, I don't use any sealer with paper gaskets, but to each their own.

[Walt Fricke]

I once had a leak like you describe - it appeared to be between the chain housing and the cam tower. As I drove my car with a newly rebuilt engine to my trailer to load, there was a trail of oil - not a pesky drip you can live with for quite a long time.

Turns out I had forgotten to tighten the three 10mm head bolts. As soon as I had the cam gear off this was obvious. Tightened, reassembled, and good to go. I checked the cam timing, but since I hadn't moved the crank or cam, it went back together timed just fine and I didn't have to do anything more. If you moved either, then you must retime. But if you didn't, check as it is before fussing with the timing.

The #4 intake and exhaust rocker shafts can make it look like a leak is in this area. The diagnostic is a rocker shaft which has moved enough that you wouldn't have left it in that position on a rebuild.

It looks to me like you used a non-hardening sealant? I've had good luck with those for some applications. Though in this application you seldom have to pull that aluminum holder - not like, say, valve cover gaskets, where you should periodically take the covers off to check this or that.

Anyway, what did you see under the valve covers?

[Nditiz1]

Thanks Walt. I will double check them. I did pull them prior to installing the engine. I first saw this leak on the engine stand. The bores between the closest rocker on the intake and exhaust were dry. I had put on RSR seals on the rockers prior to the initial start. Double checking the head bolts is not a bad idea.

[Nditiz1]

Ok both bores look to be dry. Both the bores where the rockers shafts sit had no pools of oil. This pic shows the lower bore next to the chain case. Almost looks like it streamed down from the cam hole.

Also, I retorqued all the hardware in here. The 18 (less 6 I could not reach) were all in spec. The 12 head nuts were mostly in spec. A few moved slightly, but nothing that would lead me to believe they did not have a good bond.

[Walt Fricke]

Well, I guess things all point to the cam seals. If the orange O ring looked OK (not torn or damaged), the three bolt gasket has got to be the prime suspect, despite the fact that it should seal with no sealants, etc. Nothing much to lose by applying a sealant there -- the worst that can happen is a PITA if you ever have things apart again. Lots of PITAs in reassembling an engine, especially if you only do it every few years.

I don't think you would see a significant oil leak from the chain guide pins, if a one or more of the factory epoxy seals had failed - just an irritant, and oil on the lower backside of the chain housing, away from where the cam is.

By the way, how did you run pressurized oil through your engine while on the engine stand? Do you have one complete with oil tank, gas can, starter, and all the fixins?; As I recall, Tony made one up so he can test engines he rebuilds in the comfort of his basement, before he hauls them back up to where cars are. Like most, I've had to install the engine before I can see if it will start, idle well, not leak, etc.

[Eagledriver]

I’ve seen leaks here from the “plate” being warped from over tightening. The solution is to sand it flat again on a flat surface. It’s the aluminum piece with the 3 bolts holding it on.